Electricity is an invisible phenomenon. Usually, the state of the electrical equipment is indicated using some form of illuminator such as LEDs arranged in a housing. The light from the illuminator indicates whether the equipment is on or off.
U.S. Pat. No. 6,347,172 describes an optically observable cable and a method of manufacturing the same. The optically observable cable includes a conduit for conducting signals and a side-emitting optical fiber disposed on a periphery of the conduit and extending along a length of the conduit, and a cable jacket encapsulating the conduit and the side-emitting optical fiber, wherein the cable jacket is at least partially translucent such that the side-emitting optical fiber is optically exposed through the cable jacket. A method of detecting individual cables from amongst a plurality of signal transmission cables each having a side-emitting optical fiber includes positioning a light source at an interface which houses and end of a cable to be detected, transmitting light from the light source into the interface, and observing light emitted from an axis of a cable to be detected. This invention aims to solve the problem of identifying different cables in a large number of cable structures.
In the prior art, materials emitting light when an electric current passes through them are well known and used in a wide range of display applications. Typical electroluminescent devices comprise an anode, normally of an electrically light transmitting material, a layer of a hole transporting material, a layer of the electroluminescent material, optionally a layer of an electron transmitting material and a metal cathode. There can be other layers, such as buffer layers and the layers can be combined using mixtures of one or more of the hole transporting material, electroluminescent material and the electron transmitting material.
For example, WO 03/093394 relates to an electroluminescent device having a layer which emits light in the blue, purple/blue or ultraviolet section of the spectrum and a layer which contains a fluorescent material and optionally a layer comprising one or more color filters so that light emitted by the electroluminescent layer excites the fluorescent material causing light to be emitted at a longer wavelength.
US 2002/0039666 relates to an electric luminescence fiber, which can be maintained in any desired shape and can be used in wider applications. The invention provides a flexible luminescence substance produced by arranging electrode wires in electric luminescence powder, said electric luminescence substance is coated with thermoplastic resin, thermosetting resin, or UV-setting resin. The coated resin is hardened and stabilized in linear or other desired shape, and the electric luminescence substance inside the coated resin is maintained in the desired shape.